This is so good, you would not guess its made from leftovers. Leftover mashed potato soup!
I made mashed potatoes the day before. Next day, I sauted some onion in butter, added the leftover mashed potatoes, a bit of ham cubed (leftover ham, as well) and added milk. A little less milk that potatoes. A little salt and pepper, and a shake or 2 of celery salt.